* {
  padding: 0px;
  margin: 0px;
  list-style: none;
  bottom: 0;
  text-decoration: none;
}
body {
  /* flex布局 https://www.runoob.com/w3cnote/flex-grammar.html */
  display: flex;
  /* 子盒子中心对齐 */
  justify-content: center;
  /* 定义项目在交叉轴上如何对齐 */
  align-items: center;
  height: 100vh;
  background-color: rgb(170, 190, 250);
}
